Dental apparatus



April 15 1 924 7 1,490,090

" M. F. BURNS DENTAL APPARATUS Filed OCD. 24, 1922 rill/111111111111;

l/WENTUR Arron/m Patented Apr. 15, 1924.

MARTIN F. BURNS, OF ASTORIA, NEW YORK.

DENTAL APPARATUS.

Application filed October 24, 1922. Serial No. 596,553.

To all whom it may concern.

Be it known that I, MARTIN F BURNS, a citizen of the United States, and a resident of Astoria, county of Queens, and State of New York, have invented certain new and useful Improvements in Dental Apparatus, of which thefollowing is aspecification.

This invention relates to dental apparatus and more particularly to dental flasks and to investment holders used in casting plates, bridges, inlays and other restorations.

In casting a plate, bridge or other restoration, a dentist first makes a pattern in wax of the article tobecast. The pattern is then placed in an investment holder and is invested in an initially plastic and quick hardening composition. lVhen the in vestment is dry or has set, the wax is melted out or otherwise, dissipated and the cavity is filled wit-h molten metal. The metal is forced into the cavity under pressure to effect the complete filling of the cavity. The casting is then allowed to cool and is preferably cooled slowly to pre vent warping or distort-ion.

hen the apparatus is used for casting inlays, the casting is comparatively small and therefore it is desirable to use a small investment holder. This saves investment and greatly expedites the making of the casting since the wax pattern can be quickly melted out and the metal can be poured and will cool in a very short space of time. One of the objectsof the invention is to provide apparatus of the class described so constructed and arranged as to expedite the making of small castings.

Another object of the invention is. to provide an investment holder so constructed and arranged that the holder can be removed from. the receptacle in connection with which it is used and the wax pattern can be melted or dissipated by inverting the holder and applying heat directly to the sides thereof.

Another object of the invention is to provide an investment holder constructed in such a, manner that the holder can be invested and the wax pattern can be melted or dissipated without the use of an outer receptacle. i

Further objects of the invention will appear from the following specification taken in connection with the drawings, which form a part of this application, and in which Fig. 1 is a top plan view of an investment holder constructed in accordance with the invention. i

Fig. 2 is an elevational view partly in section showing the investment holder shown in Fig. 1 and outer. receptacle used in connection therewith.

Fig. 3 is a view similar to Fig. 2,but showing a slightly modified form of receptacle.

Fig. 4 is a top plan view of another form of investment holder and outer receptacle.

Fig. 5 is an elevational view partly in section of the construction shown in Fig. 4,

Fig. 6 is a top plan view similar to Fig. 1, but showing a slightly different shape of investment holder, and

Fig. 7 is a sectional elevation of a portion of an investment holder and receptacle showing another embodiment of the inven tion.

The invention briefly described consists of an investment holder so constructed that the holder may beinvested and the wax pattern may be melted therefrom with or without the use of an outer receptacle. The holder and receptacle are! provided with interengaging means whereby the holder is supported on the receptacle. In the embodiment of the invention shown in Figs. 1 to 3 and 6, the investment holder is pro-- vided with a laterally extending flan 'e adapted to rest on the upper edge of tie receptacle. In the form of the invention shown in Figs. 4. and 5, the receptacle has formed thereon an internal flange or led e upon which the holder is. supported. ln this latter form of the invention also the upper edge of the investment holder extends upwardly beyond the upper edge of the receptacle.

Referring to the drawings, the outer receptacle 10 is substantially cylindrical in shape and the investment holder is formed with a portion 11 adapted to fit within the wall of the receptacle and with a portion 12 reduced in section and spaced from the receptacle, these portions being joined by a flange or ledge 13.

In the embodiments of the invention shown in Figs. 1 to 3 inclusive the holder cit;

has formed thereon a laterally extending flange 14 which is adapted to rest as shown in Figs. 2 and 3 on the upper edge 15 of the receptacle 10, thereby supporting the holder on the receptacle.

In Fig. 3 the receptacle is shown as having an inwardly extending annular ledge 16 positioned to engage the end surface of the flange 13 of the holder, thereby forming a supplemental support.

In Figs. t and 5 the receptacle has the inwardly extending ledge 16 for supporting the holder and the upper edge of the holder extends above the upper edge 15 of the receptacle.

In Fig. 6 the construction is substantially the same as that shown in Figs. 1 to 3, differing therefrom only in the shape of the lower portion 12 of the investment holder, this be ing shown at 18 as elliptical. it will be understood, of course, that any other desired shape may be used, if desired.

In Fig. 7 the investment holder 20 is substantially cylindrical throughout its length and has a flange 14 at its upper end resting on the upper end 15 of the receptacle.

The use of the investment holder will now be briefly described. Because of its peculiar construction, the investment holder illustrated may be used in several different ways. For instance, referring first to the form of the invention shown in Figs. 1 to 8 inclusive, the wax pattern may be invested in the holder without the use of the outer receptacle since the holder is sufliciently rugged in construction topermit the investing of the pattern without requiring additional support. In this way a plurality of holders may be invested. If the pattern is invested with the sprues extending upwardly the holder is then placed in the receptacle and heat is applied to the air space between the portion 12 of the holder and the wall of the receptacle. This heat will then melt the wax which will be dissipated through the openings left when the sprues are withdrawn. The holder and receptacle are then placed in the casting machine and the molten metal is forced under pressure into the cavity in the usual manner. If, however, the pattern is invested with the sprues extending downwardly through the portion 12, the investment holder may then be inverted and heat may be directly applied to the wall of the portion 12 of the investment holder, thereby melting and boiling out the wax. If used in this manner, no outer receptacle is necessary until the inlay or other restoration is to be cast. When the holder shown in Figs. 1 to 3 and 6 is placed with the receptacle in the casting machine the compressed air is forced directly into the investment holder and cannot escape into the receptacle, due to the overhanging flange 14 in the holder.

The deiice shown in Figs. 4; and 5 may be used in the same manner as that shown in Figs. 1 to 3 and 6. With the construction shown in Figs. 4L and 5, however, the upper edge 17 of the holder is extended above the upper edge 15 of the receptacle in order to confine the compressed air to the holder and to prevent any of the air from passing between the receptacle and the holder.

Although certain specific embodiments of the invention have been particularly shown and described, it will be understood that the invention is capable of further modification and that further changes in the construction and in the arrangement of the parts may be made without departing from the spirit or scope of the invention as expressed in the following claims.

What I claim is:

1. Dental apparatus comprising an open ended receptacle, and an open ended investment holder adapted to fit within said receptacle and having a laterally extending flange adapted to rest on the upper end of the receptacle.

2. Dental apparatus comprising an open ended receptacle, and an open ended investment holder adapted to fit within said receptacle and having a laterally extending flange adapted to rest on the upper end of the receptacle, and a portion of reduced section longitudinally spaced from said flange.

3. Dental apparatus comprising an open ended receptacle and an open ended investment holder comprising a portion adapted to fit snugly within said receptacle and a portion of reduced section spaced from the wall of the receptacle and a ledge connecing said portions.

4:. Dental apparatus comprising a receptacle and an open ended investment holder comprising a portion adapted to fit snugly within said receptacle and a portion of reduced section spaced from the wall of the receptacle, a ledge connecting said portions, and means for supporting the holder on the receptacle.

5. Dental apparatus comprising a receptacle and an open ended investment holder comprising a portion adapted to fit snugly within said receptacle and a portion of reduced section spaced from the wall of the receptacle, a ledge connecting said portions and means formed on the upper end of the holder for supporting the holder on the receptacle.

6. Dental apparatus comprising a receptacle and an open ended investment holder comprising a portion adapted to fit snugly within said receptacle and a portion of reduced section spaced from the wall of the receptacle, a ledge connecting said portions and means on the receptacle for support ing the holder on the receptacle.

7. An open ended investment holder comprising ai substantially cylindrical upper portion, a substantially cylindrical lower portion of reduced section connected to the upper portionby a flange.

8. An open ended investment holder hav- 5 ing a substantially cylindrical upper portion and a reduced lower portion.

9. An investment holder open at both ends and having a substantially cylindrical upper portion and a reduced lower por- 10 tion and an annular flange extending outwardly portion.

10. An investment holder open at both ends and comprising a substantially cylindrical member having an annular outwardly extending flange at its upper end.

In witness whereof, I have hereunto set my hand this 21st day of October, 1922.

MARTIN F. BURNS.

from the upper end of the upper 

